Adaptive inverse control of chatter vibrations in internal turning operations

• Published in: Mechanical systems and signal processing Vol. 129; pp. 91 - 111
• Main Authors: Fallah, M., Moetakef-Imani, B.
• Format: Journal Article
• Language: English
• Published: Berlin Elsevier Ltd 15-08-2019; Elsevier BV
• Subjects: Accelerometers; Active noise control; Active vibration control; Actuators; Adaptive algorithms; Adaptive control; Aluminum base alloys; Boring; Boring bar; Chatter; Chatter suppression; Control algorithms; Control theory; Controllers; Cutting tools; Feedback control; Feedforward control; FxNLMS algorithm; SISO (control systems); Stability; Stability improvement; Structural steels; Surface layers; Tool steels; Turning (machining); Vibration control; Workpieces; Boring bar; Active vibration control; Chatter suppression; Stability improvement; FxNLMS algorithm
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2019.04.007

•This article addresses the adaptive inverse control of boring bar chatter in internal turning process.•The feedback Filtered-x Normalized Least Mean Square algorithm is implemented in practice.•The parameters of controller are obtained from impact tests, without a priori knowledge of cutting dynamics.•The feedback FxNLMS controller suppresses the self-excited chatter vibrations by at least 70 dBs.•The boundary of stability in internal turning process is raised by at least 10 folds.
In this article, adaptive inverse control of chatter vibrations in internal turning process is addressed. The active boring bar is composed of a slender steel cutting tool, an electrodynamic shaker as controllable actuator and an IEPE accelerometer as feedback sensor. The SISO control system actuates in the direction normal to the cut surface. A novel adaptive inverse control algorithm is presented in this paper. This algorithm is mainly used in the feed-forward Active Noise Control (ANC) applications and is known as the Filtered-x Normalized Least Mean Square (FxNLMS). In order to extend the application of adaptive inverse control algorithms in the field of Active Vibration Control (AVC), the FxNLMS algorithm with feedback architecture is suggested for the specific problem of chatter suppression in internal turning operations.
The performance of developed adaptive feedback controller is experimentally verified during the internal turning of Aluminum alloy 6063-T6. The value of critical limiting depth of cut is anticipated to be nearly 0.2 [mm] for the slender boring bar. However, the stable cutting process is conducted by the active boring bar in the presence of adaptive controller up to depth of cut 2 [mm]. That is, the boundary of stability is enhanced by at least 10 folds. It has been observed that the amplitude of chatter vibrations is efficiently suppressed adjacent to the fundamental resonance peak of the active boring bar. In addition, the feedback FxNLMS controller effectively attenuates the boring bar’s vibration by at least 70 dBs. Moreover, the periodic chatter marks are eliminated from the surface texture of workpiece and the roughness of cut surface is remarkably improved. The obtained results suggest that the practical application of adaptive inverse control algorithms for chatter rejection can be extended to other machining processes as well.